Applicant is aware of the following patents and publications, the disclosures of which are incorporated by reference herein:
U.S. Pat. No. 4,083,441 U.S. Pat. No. 4,522,120 U.S. Pat. No. 4,569,282 U.S. Pat. No. 4,838,015 U.S. Pat. No. 5,783,816 EP 0,573,342
A mechanical twine wrapping device is known from U.S. Pat. No. 4,083,441 (DE 27 38 500). In this design, the bale length is determined by a rotatable star wheel. The rotary movement of the star wheel is transmitted by a toothed segment and a connecting lever to a pivotably mounted stop in the clutch region. As soon as the pre-selected bale length is reached, the actuation of the clutch is controlled by the stop, and the process of twine wrapping the bale is triggered. Sufficient reliability of operation is achieved in balers of small and medium capacities with this design. However, as a result of higher pressing capacities and working speeds, such a design does not provide reliable and trouble-free operation under all the conditions, particularly in the conditions which occur in big square balers.
Electrical actuating devices for the clutch of the twine wrap device, such as those on big square balers, have also been developed. For example, from EP 0 573 342, a baler is known on which the twine wrap device is controlled by a star wheel, which determines the bale length, in conjunction with an electrical sensor. When the bale reaches a specified length, the sensor sends a signal to a control device which emits a control signal to the device for triggering the twine wrapping process. The triggering device is comprised of a lifting magnet, which is actuated by the control signal, and a clutch. When the lifting magnet is actuated, the clutch is switched by the lifting motion of the lifting magnet's ram. However, voltage fluctuations within the electrical wiring of the baler can prevent the lifting magnet from exerting a sufficient force to trigger the clutch, and may lead to malfunctions during the twine wrapping process.